Fluorescent lamp



United States Patent O 1 3,024,383 FLUORESCENT LAMP Ulrich W. Doering, 37 Ainmillerstrasse, Munich, Germany Filed May 23, 1955, Ser. No. 510,115 In Germany Oct. 1, 1948 Public Law 619, Aug. 23, 1954 Patent expires Oct. 1, 1968 4 Claims. (Cl. 313 204) The invention refers to electrical discharge lamps with a filling of rare gases at low pressures of several mm., preferably with an addition of metal vapor e.g. mercury vapor, which is to be operated from the line voltage and by means of usual sockets and fixtures. The light emitted will be generated by means of fluorescent materials covering the inside walls of the vessel and surrounding the discharge path. The lamp is provided with cold electrodes or, with larger or longer types, preferably with electrodes of the hot activated type arranged near the same end of theelongated cylindrical or tube-like lamp bulb. The lamp is preferably socketed exclusively at one end, so that it has a candle-like form. Therefore it may be inserted just as the common incandescent lamps. As compared with the latter it can be built even for loads as low as 1-5 watt and operated at a rate of ten lumens per watt and many times better than the glow lamps known heretofore and surpassing the rate for corresponding tube-like incandescent lamps by several times. Like other fluorescent lamps it yields many more colours and tints than incandescent lamps. Smaller types can be operated by means of a resistance e.g. provided within the socket. Larger types will be operated preferably by means of chokes or transformers like known fluorescent lamps.

The usable lifetime is up to 10 times that of incandescent lamps. The lamp may be used as a permanent illumination, as a small-size illumination for staircases, lobbies, telephone booths, hospitals, switch boards or as a practical and ornamental candle-like lamp especially for interior lighting.

Referring to the drawings which however merely represent possible embodiments of the invention, it may be described more in detail.

FIG. 1 represents a longitudinal sectional view of the tube-like lamp, wherein a partition 8 of its interior is shown cut perpendicular to its plane.

FIG. 2 is a section of said partition in and along its plane.

FIG. 3 is a cross section of a special embodiment of the lamp tube.

FIG. 4 is a cross section of another embodiment of the lamp having a four-winged partition or two intersecting partitions.

In the longitudinal sectional view of FIG. 1 reference character 1 is an elongated and, as far as possible, strictly cylindrical bulb of e.g. 15 cm. length and about 3-6 cm. diameter, into which is sealed the short reentrant stem 2 and to which is cemented the base 3. The leadwires 4 and 5 emerge from the squeezed portion of the stem preferably within small glass tubes 6 and 7 aflixed to the latter. Perpendicularly to the plane of the squeezed portion and along a symmetrical longitudinal section of the tube-like envelope a long, flat and thin disk or plate 8 is arranged, with its lower part inserted between the leadwires or between the enclosing tubes 6 and 7 and the plate-like electrodes 12 and 13. Advantageously it rests crosswise at 10 in FIG. 2 on the squeezed portion of the stem or on a disk-like base 11 interposed in FIG. 1. It

. subdivides therefore the interior of the tube into two semicircular halves. However it is chosen shorter than this, so that it leaves a connection between the semicircular channels by way of a recess 9 at the top of the tube.

3,024,383 Patented Mar. 6, 1962 The disk or plate consists as a whole of an inorganic material, which is non-gassing and elastic. Especially it may consist of a sheet of fibre glass or fibre glass-textiles, preferably bound or stiffened by measured sintering, by impregnating and sintering with boron-trioxyde, borates, phosphates, silicates, etc. A plate like this abuts elastically and therefore tightly over the whole length of its edges against the glass walls of the enclosing tube and thereby prevents short circuiting of the discharge from one branch of the discharge channel to the other, what otherwise inevitably would happen through leaks and slots as narrow as a few tenths of a mm. under the pressure of the operating and especially of the starting voltage of up to 500 and 600 volts. Instead, a thin sheet 8 as shown in FIG. 2 of inelastic glass or ceramic may be used trimmed however with compressible or elastic borders or linings 16 and 17 of fibre glass which elastically abut against the inner surfaces of the envelope and prevent short circuiting.

In the process of mass production of bulbs and even more of glass tubes it is not possible to draw tubes of 3-5 cm. diameter with an accuracy of better than 10.5 mm. over a length of 15-50 cm. without increasing the manufacturing costs enormously. Similar conditions apply to the making of glass sheets for the partition and a plate which has to form a seal at the base of the partition. On the other hand, sealing the latter and the base to the wall of the envelope makes the lamp liable to cracking or requires extended and costly annealing processes.

The edge of the glass textile or fibre glass plates may be thickened, unraveled or provided with additional linings 16 and 17 of fibre glass. The thickness may be as small as four-tenths of a mm. At the squeezed portion of the stem the lumen of the envelope is obliterated by a plate like pad or disk 11 in FIG. 1, which is so dimens tioned so that it presses against the wall of the tube 1; and on or in a groove of disk 11 rests tightly the lower rim of the partition 8. Disk 11 also encloses tightly the electrode wires 4 and 5 of the respective tubes 6 and 7. The discharge is forced to go from the electrode 12 through the right half-side 14 of the envelope, by way of the recess 9, through the left half side 15 of the interior of the envelope to the electrode 13. The partition 8' will be kept tightly in place by elastically abutting against the enclosing envelope by means of its sideways edges and additionally if required by the electrodes 12 and 13 pressing with at least parts of their structure against it from opposite sides.

The envelope 1 may have a cross-section as indicated by FIG. 3. The partition 8 with its borders 16 and 17 separates it into two bulging and therefore improved discharge channels 18 and 19.

As indicated by FIG. 4 the useful discharge path may be lengthened or the tube may be shortened by employing two partitions 8 and 23 arranged perpendicularly one to another and partly intersecting each other. The electrodes advantageously may be given the form of rectangular metal sheets 20 and 21 preferably arranged at the same side of the one partition 8 and at different sides of the other partition 23. The one partition 8, at least with its lower part, is arranged somewhat asymmetrically leaving enough space for the tubes 6 and 7 enclosing the leadwires, or the latter may be arranged somewhat sidewise on the stem. The electrodes 20 and 21 preferably may grip the partition 23 tightly between them and border against partition 8 so as to hold both of them in place. The incisions in the partitions may be thickened or conveniently trimmed with fibre glass linings so as to tighten and prevent electrical leakage. The discharge goes from electrode 20 and the bottom of the tube by way of a passage or recess at the upper edge ofpartition 8 to the discharge channel 22, therein downwards in the direction to the socket of the lamp, by way of a passage or recess provided at the right half of the lower edge of the partition 23 to the discharge channel 24, therein upwards again at last by a passage or recess at the upper half edge of the partition 8 into discharge channel 25 and at last downwards to electrode 21. To provide for the upper recess in a simple manner, the one partition 8 may be shorter than the other one 23, which with its upper edge closely follows the configuration of the upper cavity of the lamp and tightly abuts against its inner surface.

To facilitate the starting of the lamp, especially one having a rather elongated discharge, a special conductive lead for the initial discharge may be provided as indicated by the spiral 26 of high resistance wire in FIG. 1, which is preferably connected elastically to the one electrode 12, extends along the partition 8 to its upper edge, crosses over the other side, and preferably tightly fitting to its surface runs down as far as to the proximity of the electrode 13. It may be mechanically connected with the latter thereby being held in place, however, not electrically. Such a starting means may preferably consist of a thread of fibre glass overwound with very fine resistance wire or covered with a very thin layer of graphite, metal or conductive metal compounds. Its electric resistance equals only a very small fraction e.g. of of that of the discharge path in operation.

Fluorescent materials cover at least the inner surface of the envelope and the partition too. However, the latter may be preferably covered by highly ultraviolet reflective layers consisting preferably of magnesium oxide, alkaline earth-phosphates or finely divided silica powder.

What I claim is:

1. An electric gas and vapour discharge lamp comprising a substantially cylindrical bulb, a filling of low pressure, fluorescent materials covering at least partly the discharge channel, two electrodes close to another at the same side of the bulb, a thin and fiat partition subdividing the interior of the bulb and arranged between the electrodes consisting of a rigid inorganic material and having a trimming of fibre glass attached to the edges of the plate, elastically abutting against the inner surfaces of the bulb, a recess and passage left between the end of the partition and the top of the envelope.

2. An electric discharge lamp comprising a substantially cylindrical bulb, a filling of low pressure, fluorescent materials provided on at least a part of the inside surfaces, a seal closing the bulb at one side, lead wires penetrating the seal, two electrodes mounted on the seal close to another at one side of the bulb, a partition between them and extending through the interior of the lamp, how ever, sparing a passage at the other end of the bulb, a pad of fibre glass arranged across the lumen of the bulb at the seal, said partition consisting at least at its edges of fibre glass and resting with one corresponding smaller edge on the pad.

3. An electric gas and vapour discharge lamp, a sub stantially cylindrical bulb, fluorescent materials covering at least in part the internal surfaces of the lamp, two electrodes mounted on the same seal at one side of the bulb close to another, a partition between them subdividing the interior of the bulb, edges of the partition consisting of fibre glass, said electrodes pressing with parts of their structure against the partition interposed.

4. An electric gas and discharge lamp, comprising a compact substantially cylindrical bulb, a filling of low pressure, fluorescent materials covering at least in part the inside surfaces along the discharge channel, two electrodes mounted on the same seal at the same side of the bulb, a quadrangular partition consisting at least at its edges of fibre glass, separating the electrodes and subdividing the interior of the bulb into four longitudinal channels, a pad of fibre glass arranged across the lumen of the bulb near the seal, passages provided alternately at respective ends of three successive wings of the partition, said electrodes provided at the same end of the bulb in adjacent channels so as to cause the discharge to meander four times through the bulb.

References Cited in the file of this patent UNITED STATES PATENTS 1,935,423 Wayringer Nov. 14, 1933 1,951,138 Ewest et al. Mar. 13, 1934 2,121,333 Barclay June 21, 1938 2,133,205 McCauley' Oct. 11, 1938 FOREIGN PATENTS 906,947 France June 4, 1945 

1. AN ELECTRIC GAS AND VAPOUR DISCHARGE LAMP COMPRISING A SUBSTANTIALLY CYLINDRICAL BULB, A FILLING OF LOW PRESSURE, FLUORESCENT MATERIALS COVERING AT LEAST PARTLY THE DISCHARGE CHANNEL, TWO ELECTRODES CLOSE TO ANOTHER AT THE SAME SIDE OF THE BULB, A THIN AND FLAT PARTITION SUBDIVIDING THE INTERIOR OF THE BULB AND ARRANGED BETWEEN THE ELECTRODES CONSISTING OF A RIGID INORGANIC MATERIAL AND HAVING A TRIMMING OF FIBRE GLASS ATTACHED TO TEH EDGES OF THE PLATE, ELASTICALLY ABUTTING AGAINST THE INNER SURFACES OF THE BULB, A RECESS AND PASSAGE LEFT BETWEEN THE END OF THE PARTITION AND THE TOP OF THE ENVELOPE. 